/*
 * @(#)ResourceFinderModule.java
 *
 * Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
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 *
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 */

package org.wso2.balana.finder;

import org.wso2.balana.ctx.EvaluationCtx;

import org.wso2.balana.attr.AttributeValue;

/**
 * This is the abstract class that all <code>ResourceFinder</code> modules
 * extend. All methods have default values to represent that the given feature
 * isn't supported by this module, so module writers needs only implement the
 * methods for the features they're supporting.
 * 
 * @since 1.0
 * @author Seth Proctor
 */
public abstract class ResourceFinderModule {

	/**
	 * Returns this module's identifier. A module does not need to provide a
	 * unique identifier, but it is a good idea, especially in support of
	 * management software. Common identifiers would be the full package and
	 * class name (the default if this method isn't overridden), just the class
	 * name, or some other well-known string that identifies this class.
	 * 
	 * @return this module's identifier
	 */
	public String getIdentifier() {
		return getClass().getName();
	}

	/**
	 * Returns true if this module supports finding resources with the
	 * "Children" scope. By default this method returns false.
	 * 
	 * @return true if the module supports the Children scope
	 */
	public boolean isChildSupported() {
		return false;
	}

	/**
	 * Returns true if this module supports finding resources with the
	 * "Descendants" scope. By default this method returns false.
	 * 
	 * @return true if the module supports the Descendants scope
	 */
	public boolean isDescendantSupported() {
		return false;
	}

	/**
	 * This is an experimental method that asks the module to invalidate any
	 * cache values it may contain. This is not used by any of the core
	 * processing code, but it may be used by management software that wants to
	 * have some control over these modules. Since a module is free to decide
	 * how or if it caches values, and whether it is capable of updating values
	 * once in a cache, a module is free to intrepret this message in any way it
	 * sees fit (including igoring the message). It is preferable, however, for
	 * a module to make every effort to clear any dynamically cached values it
	 * contains.
	 * <p>
	 * This method has been introduced to see what people think of this
	 * functionality, and how they would like to use it. It may be removed in
	 * future versions, or it may be changed to a more general message-passing
	 * system (if other useful messages are identified).
	 * 
	 * @since 1.2
	 */
	public void invalidateCache() {

	}

	/**
	 * Tries to find the child Resource Ids associated with the parent. If this
	 * module cannot handle the given identifier, then an empty result is
	 * returned, otherwise the result will always contain at least the parent
	 * Resource Id, either as a successfully resolved Resource Id or an error
	 * case, but never both.
	 * 
	 * @param parentResourceId
	 *            the parent resource identifier
	 * @param context
	 *            the representation of the request data
	 * 
	 * @return the result of finding child resources
	 */
	public ResourceFinderResult findChildResources(
			AttributeValue parentResourceId, EvaluationCtx context) {
		return new ResourceFinderResult();
	}

	/**
	 * Tries to find the child Resource Ids associated with the parent. If this
	 * module cannot handle the given identifier, then an empty result is
	 * returned, otherwise the result will always contain at least the parent
	 * Resource Id, either as a successfully resolved Resource Id or an error
	 * case, but never both.
	 * 
	 * @deprecated As of version 1.2, replaced by
	 *             {@link #findChildResources(AttributeValue,EvaluationCtx)}.
	 *             This version does not provide the evaluation context, and
	 *             will be removed in a future release. Also, not that this will
	 *             never get called when using the default PDP.
	 * 
	 * @param parentResourceId
	 *            the parent resource identifier
	 * 
	 * @return the result of finding child resources
	 */
	public ResourceFinderResult findChildResources(
			AttributeValue parentResourceId) {
		return new ResourceFinderResult();
	}

	/**
	 * Tries to find the descendant Resource Ids associated with the parent. If
	 * this module cannot handle the given identifier, then an empty result is
	 * returned, otherwise the result will always contain at least the parent
	 * Resource Id, either as a successfuly resolved Resource Id or an error
	 * case, but never both.
	 * 
	 * @param parentResourceId
	 *            the parent resource identifier
	 * @param context
	 *            the representation of the request data
	 * 
	 * @return the result of finding descendant resources
	 */
	public ResourceFinderResult findDescendantResources(
			AttributeValue parentResourceId, EvaluationCtx context) {
		return new ResourceFinderResult();
	}

	/**
	 * Tries to find the descendant Resource Ids associated with the parent. If
	 * this module cannot handle the given identifier, then an empty result is
	 * returned, otherwise the result will always contain at least the parent
	 * Resource Id, either as a successfuly resolved Resource Id or an error
	 * case, but never both.
	 * 
	 * @deprecated As of version 1.2, replaced by
	 *             {@link #findDescendantResources(AttributeValue,EvaluationCtx)}
	 *             . This version does not provide the evaluation context, and
	 *             will be removed in a future release. Also, not that this will
	 *             never get called when using the default PDP.
	 * 
	 * @param parentResourceId
	 *            the parent resource identifier
	 * 
	 * @return the result of finding descendant resources
	 */
	public ResourceFinderResult findDescendantResources(
			AttributeValue parentResourceId) {
		return new ResourceFinderResult();
	}

}
